The neurotransmitter serotonin, best known for its role in regulating mood, may also influence the severity of tinnitus, new research has found. According to a mouse study by scientists in the US and China, increasing serotonin signaling in a specific brain circuit increased behaviors associated with the neurological disorder. Since serotonin is often targeted to alleviate symptoms of depression and anxiety, this finding could help guide the development of treatments that relieve these conditions without exacerbating tinnitus. "We've suspected that serotonin was involved in tinnitus, but we didn't really understand how. Now, using mice, we've found a specific brain circuit...